Nowadays, fluid transportation devices used in many sectors such as pharmaceutical industries, computer techniques, printing industries, energy industries are developed toward miniaturization. The fluid transportation devices used in for example micro pumps, micro atomizers, printheads or industrial printers are very important components. Consequently, it is critical to improve the fluid transportation devices.
FIG. 9A is a schematic cross-sectional view illustrating a micro pump in a non-actuation status. The micro pump 7 comprises an inlet passage 73, a micro actuator 75, a transmission block 74, a diaphragm 72, a compression chamber 711, a substrate 71 and an outlet passage 76. The compression chamber 711 is defined between the diaphragm 72 and the substrate 71 for storing a fluid therein. Depending on the deformation amount of the diaphragm 72, the capacity of the compression chamber 711 is varied.
When a voltage is applied on both electrodes of the micro actuator 75, an electric field is generated. In response to the electric field, the micro actuator 75 is subjected to a downward deformation. Consequently, the micro actuator 75 is moved toward the diaphragm 72 and the compression chamber 711. Since the micro actuator 75 is disposed on the transmission block 74, the pushing force generated by the micro actuator 75 is transmitted to the diaphragm 72 through the transmission block 74. In response to the pushing force, the diaphragm 72 is subjected to a compressed deformation. Please refer to FIG. 9B. The fluid flows in the direction indicated as the arrow X. After the fluid is introduced into the inlet passage 73 and stored in the compression chamber 711, the fluid within the compression chamber 711 is pushed in response to the compressed deformation. Consequently, the fluid will flow to a predetermined vessel (not shown) through the outlet passage 76. In such way, the fluid can be continuously supplied.
FIG. 9C is a schematic top view of the micro pump shown in FIG. 9A. When the micro pump 7 is actuated, the fluid is transported in the direction indicated as the arrow Y. The micro pump 7 has an inlet flow amplifier 77 and an outlet flow amplifier 78. The inlet flow amplifier 77 and the outlet flow amplifier 78 are cone-shaped. The larger end of the inlet flow amplifier 77 is connected to the inlet passage 731. The smaller end of the inlet flow amplifier 77 is connected to the compression chamber 711. The outlet flow amplifier 78 is connected with the compression chamber 711 and the outlet passage 761. The larger end of the outlet flow amplifier 78 is connected to the compression chamber 711. The smaller end of the outlet flow amplifier 78 is connected to the outlet passage 761. In other words, the inlet flow amplifier 77 and the outlet flow amplifier 78 are connected to the two ends of the compression chamber 711. The inlet flow amplifier 77 and the outlet flow amplifier 78 are arranged in the same direction. Due to the different flow resistances at both ends of the flow amplifiers and the volume expansion/compression of the compression chamber 711, a unidirectional net flow rate is rendered. That is, the fluid flows from the inlet passage 731 into the compression chamber 711 through the inlet flow amplifier 77 and then flows out of the outlet passage 761 through the outlet flow amplifier 78.
However, this valveless micro pump 7 still has some drawbacks. For example, a great amount of the fluid is readily returned back to the input channel when the micro pump is in the actuation status. For enhancing the net flow rate, the compression ratio of the compression chamber 711 should be increased to result in a sufficient chamber pressure. Under this circumstance, a costly micro actuator 75 is required.
For solving the drawbacks of the conventional technologies, the present invention provides a fluid transportation device for maintaining the working performance and the flowrate of the fluid.